These were the US military’s Cold War black ops nuclear hit squads

You've probably heard of the term "backpack nuke" before — perhaps in the context of a video game like Call of Duty, or an action-packed television show like "24."

But what you may or may not have realized is that backpack nukes are the farthest thing from fiction, and from the 1950s to the fall of the Berlin Wall in the 1989, they sat ready to be deployed by America's black-ops nuclear hit squads — dubbed "Green Light Teams" — should the unthinkable happen and the Cold War turn hot.

Only members of the US military's elite were selected to join GLTs, where they would be stationed near Soviet-controlled Eastern Europe, inside South Korea, and even near Iran in the late 1970s.

Navy SEALs, Force Reconnaissance Marines, Army Special Forces and more were all among the top recruits for the GLT program. If a candidate's application to the GLT program was successful, they were sworn to secrecy, unable to tell even their own spouses of their mission. Had the Soviet Union heard of the existence of these teams, it would have likely created a similar program of its own as a counter, removing all value of possessing GLTs.

These operatives were trained in local languages and dialects, and told to dress like ordinary citizens, allowing them to blend in without anybody the wiser. The vast majority of their training, however, came in the form of instruction on how to use backpack nukes at the Atomic Demolitions Munitions School at Ft. Belvoir, Virginia.

There, GLT selectees were taught how to detonate nuclear weapons, and how to bury them or disguise them so that these weapons wouldn't be discovered and defused before they could do their job.

The weapon of choice for each GLT was the B-54 Special Atomic Demolition Munition. The warhead used in each SADM was taken from a US Army program dubbed the "Davy Crockett Weapon System." The Crockett was actually a recoilless rifle-fired projectile tipped with a W54 nuclear warhead with a yield of 10-20 tons of TNT.

The W54 was modified to detonate with a yield of anywhere between 10 tons of TNT to 1 kiloton, though in testing, it was proven to be able to achieve over 6 kilotons. Weighing just 51 pounds when nestled inside the SADM, it could be hefted onto an operative's back and carried for long distances almost inconspicuously.

Should the combat environment or the mission change, GLTs could also parachute or swim their SADMs into enemy territory without fears of the backpack nuke prematurely blowing up. And when the nukes were in their detonation zones, they could be disguised as anything.

Citizens of Eastern Europe or North Korea could potentially walk by beer kegs, trash cans, or even mailboxes without being any the wiser that a primed SADM sat in side, ready to unleash unholy hell upon them. Operatives were also trained to bury their backpack nukes as deep as 9 ft underground to make them undiscoverable.

SADMs could be placed near lakes or rivers to create artificial dams as obstacles for advancing Soviet forces, or in cities,

Though the SADM came with a timing mechanism to allow for a delayed detonation sequence so operatives could escape the region, GLT operatives knew that should they be called into action, they were essentially running a suicide mission. They would still have to protect the device from being detected by enemy forces, and that would necessarily involve the GLT staying nearby, armed with submachine guns, grenades and pistols.

The US military was able to keep the existence of its GLTs a closely-guarded secret until near the end of the Cold War, when their mission was somewhat accidentally disclosed to the public. Upon finding out that a number of GLTs were positioned in West Germany, local officials immediately asked the US government to remove all SADMs from German sovereign territory.

By 1989, the SADMs were retired altogether and permanently deactivated, never having been used in combat. All active GLT operatives were brought in from the cold and returned to the US, and just a few short years later, the fall of the Soviet Union signaled the end of the Cold War - thankfully, with nary a nuke being detonated in anger by either side.